1. Field of the Invention
The present invention relates to a server and client system, which selects only one object from multiple objects.
2. Description of the Background Art
In this specification and drawings, the background data, the foreground data and the mask data are also respectively referred to in abbreviated form as the background, the foreground and the mask.
Generally, a document is made up of a mixture of characters, lines and images. Recently, in order to efficiently encode such a mixed document, a technique has been proposed to decompose the document (original image data) into background data, and one or a plurality of pairs of foreground data and mask data, and to independently encode these data.
For example, according to the Mixed Raster Content (MRC), the original image data is decomposed into the foreground data that is the color information of the characters, the mask data that is the character region information, and the background data that is the image information. The background data, the foreground data and the mask data are independently encoded. When reproducing the original image data, the foreground data or the background data is selected according to the mask data for each pixel. It is also possible to decompose the original image data into the background data and two or more pairs of the foreground data and the mask data, and to encode each of these data.
Since the recent proposal of the new encoding technique JPEG2000, the JPM (JPEG2000 Multi Layer) has been proposed to select the JPEG2000 for the compression technique that is to be used for the foreground data, the mask data and the background data of the MRC model. In addition, the JPIP (JPEG2000 Interactive Protocol) has been proposed to encode, transmit and receive only the codes of the desired region within the image that has been encoded by the JPEG2000 in a network environment. A brief description will be given with respect to such proposed techniques.
First, a description will be given of the JPM. According to the JPM, the original image data is decomposed into one background data (Base Page), and one or a plurality of layout objects that are called “pairs of foreground data and mask data”. The background data of the JPM is treated as an initial page in which the layout object is plotted. The background data, the foreground data and the mask data are independently encoded, and the JPEG2000 can be selected as the encoding technique.
For example, when reproducing the original image data that has been decomposed into the background data, and the pair of foreground data and mask data, the original image data is formed from the foreground data and the background data according to the mask data. In this particular example, the background data that is formed becomes the reproduced image data. The original image can be reproduced by repeating a similar image combining procedure, even if the pairs of foreground data and mask data increase.
As a method of combining the background data and the foreground data, it is possible to employ a method (i) that selects the foreground data or the background data for each pixel or, a method (ii) that obtains a weighted average of the foreground data and the background data for each pixel.
According to the method (i), the mask data may be binary data, and the foreground data may be selected at the pixel position where the value of the mask data is “1”, while the background data may be selected at the pixel position where the value of the mask data is “0”. According to the method (ii), the mask data may be a positive 8-bit value, and the weighted average of the foreground data and the background data may be obtained for each pixel. In other words, the pixel value of the combined image may be calculated from (combined image)={(mask value)/255)}×(foreground)+[{255−(mask value)}/255]×(background). One of the methods (i) and (ii) to be employed can be specified for each pair of the foreground data and the mask data, and the method is specified in a header for each pair. The header will be described later in the specification.
The JPIP (JPEG2000 Interactive Protocol) is a forwarding protocol of a code data of the JPEG2000 in server client environment. The JPIP can access a JPM code data. The JPIP first outputs an image data according to user's request such as user understands an outline of an entire image. For example, an image data with a low resolution is displayed. The user watches the displayed image data, and changes the request. As a result, a code data of one particular area is read and decoded again.
A conventional technique extracts a code data from a code data composed of a multi object (JPM file) and partially transmits the JPM file.
However, the above technique needs to decode plural objects, when a system displays a low resolution image data because the code data is composed of a multi object. As a result, the system requires quite a lot of time for forwarding a code data and a decoding a code data.